A few things I notice that could have made it better:
1.Don't camp ( sniper montages tend to have to be fast paced in order to be more interesting)
2. Don't hard scope (except for get multiple kills eg. triple and quads etc.)
3. Synchronize your shots with the music for the full "montage" feeling
4. Try to get a lot more streaks and not just single kills.
5. (Goes with #2) Quickscope....quickscope...quickscope!
I hope I helped

.